Oscilloscope bandwidth and multi turn presets, questions

[waltr]

Step 3- connect oscilloscope probe earth clip to tp5(0v) and bench power supply shoots up to 1.44a draw

This is due to the bench power supply and the scope both connected to the same "Ground" through the AC Mains.
This is a good reason to use an isolated PS or a current limited battery.

However, the scope measurements can be done with scope "ground" connected to the PS Negative (PS Ground). You can then clip scope probe to the Positive (tp5-0V) then adjust the scope's vertical to zero.

[Denots]

This is due to the bench power supply and the scope both connected to the same "Ground" through the AC Mains.
This is a good reason to use an isolated PS or a current limited battery.

However, the scope measurements can be done with scope "ground" connected to the PS Negative (PS Ground). You can then clip scope probe to the Positive (tp5-0V) then adjust the scope's vertical to zero.

i see that makes sense, so it is the power supply causing some of the issues.
on my power supply there are 3 terminals, positive, negative and ground, the negative and ground are shorted together with a small metal plate that looks like it can be taken out.
am I right in thinking I should remove the plate and connect my circuit to just positive and negative terminals?

All these years i thought i had a reasonable understanding of basic electronics, this has just thrown that in the air lol

[waltr]

Yes, removing the plate between the negative and ground should make the supply 'float', relative to the AC Mains 'Earth'.

Good thing the bench supply has current limiting else there would have been smoke from somewhere.

[Denots]

Happy days I will give that a try, I have been keeping the dial for current as low as I can, I turn it until constant current has just turned off and leave it there, it can still draw over an amp at that point though.
You live and learn, think I might try and do an electronics course or something.